The present invention relates to a motor device with an oil-impregnated bearing which can be used for a magnetic recording and reproducing apparatus and the like.
A motor device with an oil-impregnated bearing has been used for a capstan motor of a video tape recorder and the like (see Japanese Unexamined Patent Application Laid-Open No. 8-163806).
FIG. 9 shows a conventional motor device.
Reference numeral 1 denotes a housing that holds an oil-impregnated bearing 2 and a thrust bearing plate 3. Reference numeral 4 denotes a stator printed circuit board mounted to the housing 1, to which an end 7 of a wire of a coil 6 wound around a stator core 5 is connected. Reference numeral 8 denotes a rotor plate that holds a main magnet 9 and that has a shaft 10 attached to its center, the shaft being inserted into and supported by the oil-impregnated bearing 2. Reference numeral 11 denotes a stopper member pressed into the shaft 10 so as to prevent the shaft 10 from slipping out of the oil-impregnated bearing 2. The stopper member 11 slides on the thrust bearing plate 3.
The rotor plate 8, including the stopper member 11, is rotated to smoothly slide the shaft 10 and the oil-impregnated bearing 2. At this time, as shown in FIG. 10, because of oil dripped between the shaft 10 and the oil-impregnated bearing 2 and a pumping phenomenon caused by the sliding of the oil-impregnated bearing 2 and the shaft 10, oil 12 oozes out from the oil-impregnated bearing 2 to lubricate between the shaft 10 and the oil-impregnated bearing 2. This allows the bearing to function favorably while being lubricated.
However, with the above conventional configuration, while the shaft 10 and the oil-impregnated bearing 2 are sliding smoothly, the oil 12 oozes out through the stopper member 11 as shown in FIG. 11. As the stopper member 11 rotates at high speed as shown in FIG. 12, leaking oil 12a is scattered toward the surroundings owing to centrifugal force as showing FIG. 13. The scattered oil 12a sticks to a magnetic recording tape (not shown) in a magnetic recording and reproducing apparatus. This hinders the tape from running stably.
Further, if a large amount of oil is dripped between the shaft 10 and the oil-impregnated bearing 2, it may be scattered. On the other hand, the amount of oil is insufficient, the lifetime of the bearing is shortened. Accordingly, the amount of oil must be controlled. This currently affects operability during manufacturing.
Furthermore, when the oil 12a is scattered, the amount of oil 12 otherwise contained in the oil-impregnated bearing 2 decreases. This significantly shortens the lifetime of the bearing.
The present invention solves these conventional problems. It is an object of the present invention to provide a motor device that allows manufacturing operations to be favorably performed, that is reliable and has a long lifetime, and that has a bearing enabling a tape to run stably over a long time if a magnetic recording and reproducing apparatus employs this motor device.
To accomplish this object, a motor device according to the present invention comprises a housing that holds a bearing, a shaft inserted into and supported by the bearing, oil that lubricates between the shaft and the bearing, a thrust bearing plate pressed into and fixed to the housing, and a stopper member pressed into the shaft so as to prevent the shaft from slipping out of the bearing, the stopper member sliding on the thrust bearing plate. The motor device characterizes at least any one of the following points.
(1) A cylindrical side wall integrated with the housing is located at an end side of the housing that is closer to the thrust bearing plate so as to surround an outer periphery of the stopper member, and an end surface of the side wall is higher than a top surface of the outermost periphery of the stopper member.
(2) A groove is formed around the shaft in a surface of the stopper member which is opposite the thrust bearing plate.
With this configuration, while the shaft and the oil-impregnated bearing are sliding smoothly, oil is prevented from oozing out through the stopper member and then scattering. In other words, oil can be prevented from scattering, even if the amount of oil dripped between the shaft and the oil-impregnated bearing during manufacturing is not strictly controlled so that a slightly excessive amount of oil is dripped. Consequently, such a motor device can be realized that allows manufacturing operations to be favorably performed, that is reliable and has a long lifetime, and that has a bearing enabling a tape to run stably over a long time if a magnetic recording and reproducing apparatus employs this motor device.
A motor device according to the present invention comprises a housing that holds a bearing, a shaft inserted into and supported by the bearing, oil that lubricates between the shaft and the bearing, a thrust bearing plate pressed into and fixed to the housing, and a stopper member pressed into the shaft so as to prevent the shaft from slipping out of the bearing, the stopper member sliding on the thrust bearing plate. The motor device is characterized in that a cylindrical side wall integrated with the housing is located on an end side of the housing that is closer to the thrust bearing plate, so as to surround an outer periphery of the stopper member, and an end surface of the side wall is set to be higher than a top surface of the outermost periphery of the stopper member.
Further, a motor device according to the present invention comprises a housing that holds a bearing, a shaft inserted into and supported by the bearing, oil that lubricates between the shaft and the bearing, a thrust bearing plate pressed into and fixed to the housing, and a stopper member pressed into the shaft, the stopper member sliding on the thrust bearing plate. The motor device is characterized in that a groove is formed around the shaft in a surface of the stopper member opposite the thrust bearing plate.
Furthermore, the motor device according to the present invention is characterized in that a cylindrical side wall integrated with the housing is located on an end side of the housing that is closer to the thrust bearing plate, so as to surround an outer periphery of the stopper member, and an end surface of the side wall is set to be higher than a top surface of the outermost periphery of the stopper member, and in that a groove is formed around the shaft in a surface of the stopper member that is opposite the thrust bearing plate.
Moreover, the motor device according to the present invention is characterized in that a cylindrical side wall is provided on an end side of the housing that is closer to the thrust bearing plate, so as to surround an outer periphery of the stopper member, and an end surface of the side wall is set to be higher than a top surface of the outermost periphery of the stopper member.
Further, the motor device according to the present invention is characterized in that a cylindrical side wall is located on an end side of the housing that is closer to the thrust bearing plate, so as to surround an outer periphery of the stopper member, and an end surface of the side wall is set to be higher than a top surface of the outermost periphery of the stopper member, and in that a groove is formed around the shaft in a surface of the stopper member that is opposite the thrust bearing plate.
Furthermore, the motor device according to the present invention is characterized in that an oil repellent film is formed on the end surface of the side wall. Moreover, the motor device according to the present invention is characterized in that an oil repellent film is formed on the surface of the stopper member that is opposite the thrust bearing plate, at a position peripherally outward of the groove.